CN115349200A - Wireless transmission system - Google Patents

Abstract

The present invention relates to a wireless transmission system which improves electric wave propagation for mobile communication in production facilities such as factories and factory equipment. The wireless transmission system includes: a base station that transmits and receives radio waves in a desired frequency band selected from the frequency bands of 1 GHz to 170 GHz; and an electromagnetic wave reflection device that is arranged along at least a part of a production line that is equipped with production machines that transmit and receive the radio waves, and It has a reflective surface that reflects the above-mentioned radio waves.

Description

wireless transmission system

technical field

The present invention relates to wireless transmission systems.

Background technique

Industrial IoT (Internet of Things: Internet of Things) is developing to automate the manufacturing process and introduce advanced production and process management and preventive maintenance (Predictive Maintenance) to the manufacturing site. In the Industrial Internet of Things, "Smart Factory" connects devices, machines, and management systems in the factory to the cloud and edge AI (Artificial Intelligence: Artificial Intelligence) to make the manufacturing process more efficient. It is expected to introduce high-speed, large-capacity, low-latency mobile communication technologies such as 5G that can connect multiple devices at the same time to the communication network of the Industrial Internet of Things that handles large amounts of data. In addition to the inherent mobility and softness of mobile communication technology, it can be said that the low-latency characteristics of 5G are also suitable for industrial IoT.

The joining structure of the translucent electromagnetic wave shielding board used for buildings, such as a smart building, is proposed (for example, refer patent document 1).

Patent Document 1: Japanese Patent No. 4892207

The communication environment in production facilities such as factories and factory equipment is different from the environment of public mobile communication. In production facilities, there are various machines and structures that hinder the propagation of radio waves for communication, making it difficult to achieve high communication quality.

Contents of the invention

An object of the present invention is to provide a technique for improving electric wave propagation for mobile communication in a production facility.

In one mode of the present disclosure, the wireless transmission system has:

a base station that transmits and receives radio waves in a desired frequency band selected from frequency bands ranging from 1 GHz to 170 GHz; and

The electromagnetic wave reflecting device is arranged along at least a part of a production line in which production equipment for transmitting and receiving the radio waves is arranged, and has a reflecting surface that reflects the radio waves.

With the electromagnetic wave reflection device of the above structure, the radio wave propagation of mobile communication is improved in production facilities such as factories and factory equipment.

Description of drawings

FIG. 1 is a schematic diagram of a production line in a factory to which the present disclosure can be applied.

FIG. 2 is a schematic plan view of a wireless transmission system using the electromagnetic wave reflection device of the embodiment.

FIG. 3A is a diagram illustrating reflection at the same reflection angle as the incident angle.

FIG. 3B is a diagram illustrating reflection at a reflection angle different from the incident angle.

FIG. 3C is a diagram illustrating diffusion in multiple directions.

FIG. 4 is a diagram illustrating a basic concept of an electromagnetic wave reflection device according to an embodiment.

FIG. 5A is a diagram showing a modified example of the electromagnetic wave reflecting device.

FIG. 5B is a diagram showing a modified example of the electromagnetic wave reflecting device.

FIG. 5C is a diagram showing a modified example of the electromagnetic wave reflecting device.

FIG. 5D is a diagram showing a modified example of the electromagnetic wave reflecting device.

FIG. 6A is a configuration example of a reflective surface.

Fig. 6B is another configuration example of the reflective surface.

Fig. 6C is yet another configuration example of the reflective surface.

Fig. 6D is yet another configuration example of the reflective surface.

FIG. 7 is a diagram showing an example of connecting electromagnetic wave reflecting devices.

Fig. 8 is a schematic diagram of a connection portion of a support body.

FIG. 9A is a diagram showing an example of edge processing of a panel.

FIG. 9B is a diagram showing another example of panel edge processing.

FIG. 10A is a diagram showing a configuration example of a connection portion.

FIG. 10B is a diagram showing another configuration example of a connection portion.

FIG. 10C is a diagram showing another configuration example of a connection portion.

FIG. 10D is a diagram showing another configuration example of the connecting portion.

FIG. 10E is a diagram showing another configuration example of the connecting portion.

FIG. 10F is a diagram showing a general connection structure as a reference example.

Fig. 11A is a diagram illustrating connection of a plurality of panels.

FIG. 11B is a diagram showing the state of the electromagnetic wave reflector before connection.

Fig. 11C is a diagram showing the state of the connected electromagnetic wave reflecting device.

Fig. 12 is a diagram showing a reinforced example of the connected electromagnetic wave reflector.

FIG. 13 is a diagram showing an example of a fixing mechanism.

Figure 14 is a diagram illustrating the dimensions of a metareflector.

FIG. 15 is a diagram for examining the area size corresponding to the operating frequency and the positional relationship of transmission and reception.

FIG. 16A is a diagram illustrating a configuration relationship of a wireless transmission system.

FIG. 16B is a diagram illustrating a configuration relationship of a wireless transmission system.

FIG. 17A is a graph showing the baseline robustness of reflection mode 1. FIG.

FIG. 17B is a graph showing the baseline robustness of reflection mode 2 .

FIG. 18 is a diagram illustrating a quantification method of benchmark robustness.

FIG. 19A is a graph showing changes in phase jump in reflection mode 1. FIG.

FIG. 19B is a graph showing changes in phase jump in reflection mode 2. FIG.

Detailed ways

＜Overall image of the system＞

FIG. 1 is a schematic diagram of a production line in a factory to which the present disclosure can be applied. A production line is a strip-shaped production site that arranges equipment and machines for assembly and production into a series of processes. In the Industrial Internet of Things, by connecting industrial devices, machines, management systems, etc. used in production lines to the network, production efficiency can be improved and site safety can be ensured.

Base stations BS1 and BS2 are arranged to connect machines in the production line and the like to the network. The machines M1 and M2 used in the production line respectively have wireless communication units WT1 and WT2, communicate with at least one of the base stations BS1 and BS2, and are connected to a network.

In order to realize the wireless connection between the machines in the production line and the network, the base stations BS1 and BS2 (hereinafter, collectively referred to as "BS" as appropriate) provide a horizontally long rectangular service area. In the technical specification (TS22.104) of 3GPP (3rd Generation Partnership Project: 3rd Generation Partnership Project), which is a standardization body for mobile communications, the aspect ratio of a rectangular area in a horizontal plane is shown as a system requirement. 3 to 5 times the service area. For example, the area size of the use case called “Motion Control” is specified as 50m×10m×10m in terms of length×width×height.

In order to cover the production line in the service area provided by the base stations BS1 and BS2 and realize the network connection of the machines M1 and M2 existing in the production line, the base stations BS1 and BS2 are arranged at the ends of the production line in the length direction. aspects are valid. In order to improve communication quality and coverage, base stations BS1 and BS2 can also be coordinated and cooperated. The details of the arrangement relationship of the base station BS with respect to the production line will be described later.

FIG. 2 is a schematic plan view of the wireless transmission system 1 using the electromagnetic wave reflection device 10 according to the embodiment. The wireless transmission system 1 includes: a production line 3 configured with production machines capable of transmitting and receiving radio waves; a base station BS wirelessly communicating with machines on the production line 3 ; and an electromagnetic wave reflection device 10 disposed along the production line 3 . The electromagnetic wave reflecting device 10 has a reflecting surface 105 that reflects radio waves. Let the configuration plane of the production line be the X-Y plane, and let the height direction perpendicular to the X-Y plane be the Z direction.

The machines in the production line 3 include all production-related machines, such as tiny devices such as sensors and actuators, assembly devices, manufacturing machinery, and management systems. The machines used in the production line 3 are not limited to fixed devices or machines, and may be freely movable within the production line 3 .

The base station BS and devices M1 and M2 (refer to FIG. 1 ) having a wireless communication function transmit and receive radio waves of a specific frequency band within a range of, for example, 1 GHz to 170 GHz. Production lines and surrounding structures (such as pipes, tubes, etc.) are mostly made of metal, so radio waves are reflected and shielded. In addition, high-frequency radio waves such as the millimeter wave band have strong linear propagation performance and little diffraction, so radio waves are difficult to reach. For the equipment located in the center of the production line 3, reflections from surrounding equipment, metal products being processed, etc. become obstacles, and the communication environment may deteriorate.

If a plurality of base stations BS are arranged along the longitudinal direction of the production line 3, the communication quality can be maintained, but effective use of the work space is hindered, and the equipment cost becomes high. In the wireless transmission system 1 , the electromagnetic wave reflection device 10 is arranged along the longitudinal direction of the production line 3 , and the base station BS is arranged at the end of the production line 3 in the longitudinal direction. The electromagnetic wave reflecting device 10 suppresses the number of base stations BS installed in the production facility, and improves the wireless communication environment between the base stations BS and equipment in the production line 3 .

The electromagnetic wave reflecting device 10 may be installed substantially parallel to the long axis of the production line 3 with respect to at least a part of the production line 3 . "Approximately parallel" means that the electromagnetic wave reflecting device 10 does not need to be arranged strictly parallel to the long axis of the production line 3 . The electromagnetic wave reflection device 10 may be slightly inclined with respect to the long axis of the production line 3 within the range of effective transmission and reception of radio waves between the base station BS and the machines in the production line 3 .

The reflecting surface 105 of the electromagnetic wave reflecting device 10 reflects radio waves in a frequency band of 1 GHz to 170 GHz. The reflective surface 105 is formed by at least one of a standard reflector 101 that provides normal reflection with an incident angle equal to a reflective angle, and a metareflector 102 that has an artificial surface that controls the reflection characteristics of incident electromagnetic waves. A "metareflector" refers to a type of "metasurface" that is an artificial surface that controls the transmission or reflection characteristics of incident electromagnetic waves. In a metareflector, a plurality of scatterers that are sufficiently small compared to the wavelength are arranged, and radio waves are reflected in a predetermined direction other than the normal reflection direction by controlling the reflection phase distribution and amplitude distribution. With the metareflector 102 , in addition to reflection in directions other than normal reflection, diffusion with a predetermined angular distribution and formation of a wavefront can be realized.

FIGS. 3A to 3C show reflection modes at the reflection surface 105 of the electromagnetic wave reflection device 10 . In FIG. 3A , the electromagnetic wave incident on the standard reflector 101 is reflected at the same reflection angle θref as the incident angle θin.

In FIG. 3B , an electromagnetic wave incident on the metareflector 102a is reflected at a reflection angle θref different from the incident angle θin. The absolute value of the difference between the reflection angle θref based on the metareflector 102 and the reflection angle based on normal reflection may also be referred to as an abnormal angle θabn. As described above, by arranging metal patches or the like sufficiently smaller than the wavelength used on the surface of the metareflector 102a to form surface impedance, the reflection phase distribution is controlled and incident electromagnetic waves are reflected in a desired direction. The details will be described later, but in the case of using the electromagnetic wave reflection device 10 in the vertically long production line 3, as shown in FIG. The wireless communication unit WT of the equipment in the production line 3 is guided.

The electromagnetic wave reflected by the metareflector may not be a plane wave with a single reflection angle. By studying the surface impedance formed on the surface of the metareflector 102b, as shown in FIG. 3C , the incident electromagnetic wave diffuses in multiple directions at multiple different reflection angles θref. As a method of realizing the reflection in FIG. 3C , for example, there is a method described in "ARBITRARY BEAM CONTROL USING LOSSLESS METASURFACES ENABLED BYORTHOGONALLY POLARIZED CUSTOM SURFACE WAVES" on page 97 of "PHYSICAL REVIEW" B issue. The intensity of the diffused electromagnetic wave may be uniform, or may have a predetermined intensity distribution according to the reflection direction.

It is also possible to arrange a plurality of electromagnetic wave reflection devices 10 along the production line 3 . As long as the communication quality between the base station BS and the machines in the production line 3 can be maintained, the electromagnetic wave reflecting device can also be used as a safety barrier.

Before explaining the optimal arrangement of the base station BS relative to the production line 3, the details of the structure of the electromagnetic wave reflecting device 10 will be described below.

<Structure of Electromagnetic Wave Reflector>

FIG. 4 is a diagram illustrating a basic concept of the electromagnetic wave reflection device 10 according to the embodiment. The electromagnetic wave reflecting device 10 is vertically arranged on the X-Y plane where the production line is arranged. The height direction of the electromagnetic wave reflecting device 10 is the Z direction. The electromagnetic wave reflecting device 10 includes: a panel 13 having a reflecting surface 105 for reflecting radio waves in a desired frequency band selected from a frequency band of 1 GHz to 170 GHz; and a support 11 supporting the panel 13 .

Reflecting surface 105 of panel 13 reflects electromagnetic waves in a desired direction. The reflective surface 105 is formed of at least one of a standard reflector 101 that performs normal reflection and a metareflector 102 that has an artificial surface that controls the reflection characteristics of incident electromagnetic waves. The standard reflector 101 may also include a reflective surface formed of an inorganic conductive material or a conductive polymer material.

As long as the metareflector 102 can reflect the incident electromagnetic wave in a desired direction, or spread it with a desired angular distribution, its material, surface shape, manufacturing method, etc. are not limited. Usually, a metasurface is obtained by forming a metal patch sufficiently smaller than the wavelength used on the surface of a conductor such as a metal via a dielectric layer. The metareflector 102 is arranged at any position on the reflection surface 105 in accordance with the design of the reflection direction of the electromagnetic wave.

The size of the panel 13 can be properly designed according to the environment in which it is used. As an example, the width of the panel 13 is 0.5m-3.0m, the height is 1.0m-2.5m, and the thickness is 3.0mm-9.0mm. The size of the panel 13 may be about 1.4m×1.8m×5.0mm in consideration of the ease of transportation to the factory, installation and assembly. Part of the panel 13 may also be transparent to visible light.

The panel 13 is supported by the support body 11 so that the electromagnetic wave reflection device 10 can stand independently. The mechanical structure of the support body 11 may be any structure as long as it can stably stand up the panel 13 with respect to the installation surface (for example, X-Y plane). As will be described later, a plurality of electromagnetic wave reflection devices 10 may be used in combination. The overall height of the electromagnetic wave reflecting device 10 including the panel 13 and the support body 11 is, for example, 1.5 m to 2.5 m, and may be set to a height of about 2.0 m from the installation surface.

The support body 11 has the electrical connection part 15 which makes the potential plane of the reflection generated on the reflection surface 105 of the panel 13 continuous in addition to the mechanical design for independently erecting the panel 13 . When a plurality of electromagnetic wave reflecting devices 10 are connected and used, if the current flowing between the panels 13 of adjacent electromagnetic wave reflecting devices 10 (referred to as reflected current) is blocked by incident electromagnetic waves, the energy of the reflected electromagnetic waves is attenuated. , In addition, radiation in unnecessary directions degrades communication quality.

In the two adjacent panels, in order to ensure the continuity of the reflected current, it is preferable that the reference potential of the reflection is transmitted from one panel to the other panel through the support body 11 at high frequency, and between the two adjacent panels at high frequency. Shared reference potential. The continuity of the reflected current is preferably as uniform as possible in the connection region of the carrier 11 . The structure in which the support transmits the reference potential reflected by the reflective surface of the panel may also be referred to as a structure "referring" to the reference potential.

In order to allow one panel to transmit a reference potential and the other panel to share the reference potential through the electrical connection portion 15 of the support body 11 , it is preferable to study the processing of the edge of the panel 13 and suppress the influence on the reflection characteristics. "Edge" of the panel 13 refers to an end connecting two opposing main surfaces to each other. The specific structure of the electrical connection part will be described later with reference to FIGS. 7 to 9D.

5A to 5D show modified examples of the electromagnetic wave reflection device 10 . In the electromagnetic wave reflecting device 10A shown in FIG. 5A , the metareflector 102 is movably arranged. As for the configuration in which the position of the metareflector 102 on the reflection surface 105 is variable, any configuration may be adopted as long as the interference between the metareflector 102 and the reflection surface 105 can be suppressed. As an example, the rod 16 holding the metareflector 102 may be slidably mounted in the horizontal direction of the panel 13, and the position of the metareflector 102 on the rod 16 may be kept movable in the vertical direction.

Rod 16 may be constructed of a non-metallic and low dielectric constant material that does not interfere with the reflective properties of standard reflector 101 or metareflector 102 . The rod 16 can also be designed to have zero or minimal optical interference as well as mechanical interference at the panel interface. The metareflector 102 can be moved to an optimal position on the panel 13 according to the environment of the site where the electromagnetic wave reflecting device 10 is arranged, the positional relationship with the base station BS, and the like. As in FIG. 4 , the support body 11 has an electrical connection portion 15 inside.

FIG. 5B shows the electromagnetic wave reflecting device 10B. In the electromagnetic wave reflecting device 10B, as a reinforcement for increasing the rigidity of the panel 13 of the electromagnetic wave reflecting device 10B, a slanted column 19 may be provided on the surface of the panel 13 opposite to the reflecting surface 105 . The slanting column 19 may be erected between the support body 11 holding both ends of the panel 13 and the support body 11 , for example.

In the electromagnetic wave reflecting device 10C of FIG. 5C , reinforcing beams 21 a and 21 b are provided on the upper and lower sides of the panel 13 . The reinforcing beams 21 a and 21 b may be inserted between the supporting body 11 on both sides of the supporting panel 13 .

In the electromagnetic wave reflection device 10D shown in FIG. 5D , a slanted column 19 is provided between the reinforcing beam 21 a or 21 b and the support body 11 . These reinforcing mechanisms can suppress the vibration mode of the panel 13, stabilize electromagnetic wave reflection against the vibration of the factory floor, and reduce the weight of the large-area panel. In FIGS. 5B to 5D , an electrical connection portion 15 for referring to a reflected reference potential is provided inside the support body 11 , which is the same as in FIG. 4 .

The modified examples of FIGS. 5A to 5D can be combined with each other. For example, in the case of using the panel 13 with the structure shown in FIG. 5A , the metareflector 102 may be held movably on the reflective surface 105 side, and the slanted columns 19 may be placed on the surface opposite to the reflective surface 105 .

<Structure of reflective surface>

6A to 6D show configuration examples of the reflective surface 105 . The reflective surface 105 may have any structure as long as it reflects electromagnetic waves of 1 GHz to 170 GHz. As an example, the reflective surface 105 may be formed of a mesh conductor, a conductive film, a combination of a transparent resin and a conductive film, or the like that reflects electromagnetic waves in an arbitrary frequency band selected from the range of 1 GHz to 170 GHz.

By designing the reflective surface 105 to reflect radio waves in desired frequency bands from 1 GHz to 170 GHz, it is possible to cover the 1.5 GHz band, 2.5 GHz band, etc., which are main frequency bands currently used in mobile communications in Japan. In the next-generation 5G communication network, the 4.5GHz frequency band, 28GHz frequency band, etc. are expected. In foreign countries, 5G frequency bands are expected to include 2.5GHz frequency band, 3.5GHz frequency band, 4.5GHz frequency band, 24-28GHz frequency band, and 39GHz frequency band. It is also compatible with 52.6HGz, which is the upper limit of the millimeter-wave band frequency band of the 5G standard.

On the other hand, frequencies exceeding 170 GHz are less likely to be actually used for smart factories at this stage. In the future, when mobile communication in the terahertz band is realized indoors, photonic crystal technology or the like may be applied to extend the reflection frequency band of the reflective surface 105 to the terahertz band.

In FIG. 6A , panel 13A has reflective surface 105 of conductor 131 . The conductor 131 does not need to be a uniform conductive film as long as it can reflect 30% or more of radio waves of 1 GHz to 170 GHz. For example, it may be a mesh, a grid, or a hole array formed at a density that reflects electromagnetic waves in the above-mentioned frequency band. The repetition pitch for forming the above-mentioned density may be uniform or non-uniform. The cycle or the average cycle is preferably 1/5 or less of the wavelength of the above frequency, more preferably 1/10 or less.

Generally, the opening diameter of metal mesh fences used in factories or warehouses is 3.2cm, 4cm, 5cm, etc., and most of the electromagnetic waves from 1GHz to 170GHz pass through the fence. Even if electromagnetic waves are slightly reflected by the metal mesh fence in the vicinity of 1 GHz to several GHz, it is considered that the transmission component dominates in the frequency band above that, and stable reflection that leads to improvement of the communication environment cannot be obtained.

In FIG. 6B , panel 13B is a standard reflector and has a laminated structure of conductor 131 and dielectric 132 transparent to the operating frequency. Either surface of the conductor 131 becomes the reflective surface 105 . When an electromagnetic wave enters the conductor 131 from one side, the interface between the conductor 131 and the air becomes the reflective surface 105 . When electromagnetic waves are incident from one side of the dielectric 132 , the interface between the conductor 131 and the dielectric 132 becomes the reflective surface 105 .

The dielectric 132 holding the conductor 131 or covering the surface of the conductor 131 preferably has rigidity capable of withstanding vibrations and meets the safety requirements of ISO014120 of the ISO (International Organization for Standardization: International Organization for Standardization). Since it is used in a factory, it is preferable that even if a part or a part of a manufacturing machine collides, it can withstand impact and be able to defend, and it is more preferable that it is transparent in the visible light region. As an example, optical plastics, reinforced plastics, tempered glass, etc. having a strength greater than or equal to a predetermined value are used. As the optical plastic, polycarbonate (PC), polymethylmethacrylate (PMMA), polystyrene (PS) or the like can be used.

In FIG. 6C , panel 13C has conductor 131 sandwiched between dielectric 132 and dielectric 133 . Depending on the incident direction of the electromagnetic wave, the interface with any dielectric becomes the reflective surface 105 . The required rigidity of the dielectrics 132 and 133 is the same as that of the structure of FIG. 6B.

In FIG. 6D, panel 13D may also have metareflector 102 in part of the stack of FIG. 6B. A laminate of conductor 131 and dielectric 132 can be used as standard reflector 101 . The metareflector 102 may also be fixed on the surface of the dielectric 132 of the standard reflector 101 by bonding or the like. The region of the three-layer structure of the conductor 131 , the dielectric 132 and the metareflector 102 can become an asymmetric reflective region AS forming a metasurface. The region of the double-layer structure of the conductor 131 and the dielectric 132 without the metareflector 102 becomes a symmetrical reflection region SY capable of providing normal reflection.

In the example of FIG. 6D , the metareflector 102 is integrally assembled with the standard reflector 101 on the panel 13D as shown in FIG. 4 , but it can also be used separately from the standard reflector 101 . As a detachable structure, as shown in FIG. 5A , a position-variable metareflector 102 can also be used. By selecting the position of the metareflector 102 on the panel 13 according to the environment on site, the position of the asymmetric reflection area can be adjusted.

<Connection structure of support body>

As shown in FIG. 7 , a plurality of electromagnetic wave reflection devices 10 may be connected to each other by a support body 11 and installed on the surface P. As shown in FIG. For example, when the electromagnetic wave reflecting devices 10 - 1 and 10 - 2 are connected, the panel 13 - 1 and the panel 13 - 2 are connected at the electrical connection portion 15 of the support body 11 so that the reflected potential plane is continuous. As described above, the support body 11 has the mechanical strength to connect the panels 13 and the electrical connection performance to continue the reflected reference potential between the panels 13 . Hereinafter, a configuration example of the electrical connection portion 15 will be shown.

FIG. 8 shows an example of the electrical connection portion 15 of the support body 11 in a horizontal cross-sectional view when the electromagnetic wave reflecting device 10 stands on the surface P (see FIG. 7 ). The connection part 15 is designed to be able to transmit the reference potential of the reflection of one panel to the adjacent panel, so that the reference potential of the reflection phenomenon is shared between the adjacent panels 13 .

The support body 11 has a frame 111 and an electrical connection portion 15 provided on the frame 111 to share a reflected potential plane between the panels 13 . The connection portion 15 may have any structure as long as it can stably transmit or share a reflected reference potential between adjacent panels 13 - 1 and 13 - 2 (hereinafter collectively referred to as “panels 13 ” as appropriate). The frame 111 may be of any structure as long as it has strength capable of stably holding the electrical connection portion 15 . In the structure of FIG. 8 , the frame 111 may also be formed of an electrically insulating material.

In the example of FIG. 8 , the connecting portion 15 has conductive edge sheaths 17-1 and 17-2 (hereinafter, collectively referred to as "edge sheaths 17" as appropriate) for holding the edge of the panel 13, and the edge sheaths 17-2. The sleeve 17 is electrically connected to the bridge electrode 112 of the adjacent panel. The bridge electrode 112 is an example of a conductive bridge formed on the potential plane between the panel 13-1 and the panel 13-2. The edge sheath 17 - 1 holding the edge of the panel 13 - 1 is electrically connected to the edge sheath 17 - 1 holding the edge of the panel 13 - 2 via the bridge electrode 112 . The bridge electrode 112 is in surface contact with the edge sheaths 17-1 and 17-2, so that the electrical connection is reliable. When a reflected current is generated on the panel 13-1, the reflected current flows from the edge sheath 17-1 to the edge sheath 17-2 via the bridge electrode 112, and flows into the conductor 131 of the panel 13-1. The reflection current flows in the short current path, the creep of the current is reduced, and the reflection performance is good.

Here, the reflected current is a general-purpose three-dimensional electromagnetic field simulation software. A plane wave is incident on a model including the connection part 15, and a scattering cross-sectional area is analyzed as a reflection characteristic, and a current path is obtained from the current distribution of the cross-section, thereby determining a good range. As a solution method for the three-dimensional electromagnetic field simulation, for example, the FDTD method, the finite element method, the moment method, and the like can be used. The linear distance of the current path with respect to the panels is 50 times or less, preferably 10 times or less, more preferably 5 times or less, still more preferably 2 times or less.

In addition, the conductive material part in the connection part 15, that is, the corner part of the bridge electrode 112 or the metal layer 121 in the following modified examples is rounded in an arc shape, thereby stabilizing the scattering at the edge of the conductor, so it is preferable . The radius of curvature R at the arc-shaped chamfer is at least R=1 mm or more, preferably 2 mm or more, more preferably 4 mm or more, and still more preferably 8 mm or more.

The frame 111 is provided to secure the strength of the support body 11, and it is preferable to form the frame 111 with an insulating elastic body, resin, or the like to prevent shunting of reflected current. In addition, the above-mentioned preferable range can also be applied to the modified examples described below.

9A and 9B show examples of edge processing of the panel 13 . In FIG. 9A , panel 13 has conductor 131 sandwiched between dielectric 132 and dielectric 133 as reflective surface 105 . As an example, the edge sheath 17 may be a conductive rail with an open square or U-shaped cross section, and has a set of outer surfaces 171 and a bottom surface 172 connecting the outer surfaces 171 . A conductive adhesive material 18 such as silver paste may be pre-coated on the inner surface of the edge sheath 17 .

The conductor 131 may be folded back at the edge of the panel 13 and drawn out to the surface of at least one dielectric. When the edge of the panel 13 is inserted into the edge sheath 17 , the folded portion 131 a of the conductor 131 comes into contact with the inner wall surface of the edge sheath 17 . By leading the conductor 131 to the surface of the panel 13 at the folded portion 131a, the contact area between the conductor 131 and the edge sheath 17 is increased, and the electrical connection is stable.

As shown in FIG. 9B , the thickness of the dielectrics 132 and 133 can also be reduced along the edge of the panel 13 to form a cutout 134 . It is also possible to adopt a construction in which the edge region thinned by the cutout 134 engages with the edge sheath 17 . In this structure, the outer surface 171 of the edge sheath is aligned with the surface of the panel 13 , and the panel 13 is easy to operate.

10A to 10E show modified examples of the connection portion 15 of the support body 11 . In FIG. 10A , a support body 11A has a frame 111A formed of a carbonaceous material instead of the insulating frame 111 . The electrical connection portion 15A is formed by the frame 111A and the edge sheaths 17-1 and 17-2. As the carbonaceous material, CFRP (Carbon Fiber Reinforced Plastics: carbon fiber reinforced plastics) can be used. By combining carbon fiber and resin, the carbon fiber that is a conductor and the resin that is an insulator can be integrally molded using a continuous drawing manufacturing method to achieve high strength.

The CFRP itself holding the edge sheaths 17-1 and 17-2 becomes the electrical connection 15A. The edge sheaths 17 - 1 and 17 - 2 can be electrically connected without using the bridge electrode 112 . From the viewpoint of reflection, carbon fibers have better reflection performance than metal blocks, and the reflection characteristics of the frame 111A itself are also excellent.

In order to achieve both reflective performance and strength, the carbon fiber content of CFRP is preferably 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more. On the other hand, the resin content ratio of CFRP is preferably 50% or less, 40% or less, 30% or less, 20% or less, and 10% or less.

In FIG. 10B , a support body 11B has a frame 111B in which a metal layer 121 and a resin layer 122 are laminated. Metal layer 121 joins panels 13-1 and 13-2 in such a way as to cover edge sheaths 17-1 and 17-2. The metal layer 121 in contact with the edge sheaths 17-1 and 17-2 becomes the electrical connection part 15B. The resin layer 122 reinforces the connection between the panels by the metal layer 121 from the outside. In this structure, the creep of electric current is small. The combined structure of the metal layer 121 and the resin layer 122 facilitates the design and processing of the frame 111B. The strength of the frame 111B can also be ensured by sandwiching the metal layer 121 between the resin layers 122 when viewed from the stacking direction.

FIG. 10C connects the edge-processed panels 13 of FIG. 8 to each other. Since the surface of the panel 13 is aligned with the outer side wall of the edge sheath 17, it is only necessary to insert the panel 13 into the frame 111C with the edge sheath 17 fitted to the edge of the panel 13 in advance. Frame 111C is formed of, for example, insulating plastic. In the electrical connection portion 15C, the reflected current flows from the edge sheath 17 to the conductor 131 of the adjacent panel through the bridge electrode 112C in a short current path. Bridge electrode 112C may also be formed wide so as to be in surface-to-surface contact with the entire outer surfaces of edge sheaths 17-1 and 17-2. When the electromagnetic wave is reflected by panel 13-1, high-frequency current flows to conductor 131 of panel 13-2 through at least a part of bridge electrode 112C as indicated by a white arrow, so that current creep is small.

FIG. 10D shows a configuration example of the connection portion 15D of the support body 11D. The connecting portion 15D has a bridge electrode 114 that electrically connects the edge sheaths 17-1 and 17-2. Bridge electrode 114 electrically connects bottom surfaces 172 of edge sheaths 17-1 and 17-2 to each other. The structure of FIG. 10D is advantageous in that the high frequency flows from the conductor 131-1 to the edge sheath 17-1, the bridge electrode 114, the edge sheath 17-2, and the conductor 131-2 through the shortest path. In the example of Fig. 10D, the bridge electrode 114 connects a part of the bottom surface 172 of the edge sheaths 17-1 and 17-2, but it is also possible to increase the thickness of the bridge electrode 114, at the edge of the sheaths 17-1 and 17-2. The entire surface of the bottom surface 172 is connected. By making the bridge electrodes 114 thicker, the electrical and physical connections are more stable. By surrounding the bridge electrode 114 with the insulating frame 111D, the mechanical strength of the electrical connection portion 15D and the reliability of electrical connection are ensured.

FIG. 10E shows an example of a composite frame 111E using metal and resin. It has a metal connector 141 and a resin reinforcement part 142 covering the connector. The connector 141 is easily produced by extrusion molding or the like, ensures electrical connection, and the connector itself also has a certain degree of strength. By covering the periphery of the connector with the resin reinforcement part 142 , the strength as a support is ensured by both the connector 141 and the resin reinforcement part 142 . As a result, the thickness of the connector 141 is reduced, and the generation of residual inductance due to the detour of the current is suppressed. In addition, by rounding the ends, diffraction at the corners is prevented.

FIG. 10F shows a structure using a conventional frame 1100 formed by extrusion molding of aluminum as a reference example. In the frame 1100 having a complicated cross-sectional shape, current flows in various directions, resulting in residual inductance and stray capacitance caused by complicated detour paths of current. Since this response changes complicatedly due to incident electromagnetic waves, it adversely affects reference or transmission of the reference potential. From these points, it is preferable to adopt the structure shown in FIG. 8 and FIGS. 10A to 10E as the connection portion 15 of the support body 11 .

＜Panel link＞

Fig. 11A is a diagram illustrating connection of electromagnetic wave reflecting devices 10-1 and 10-2. Edge sheaths 17-1 are provided on the edges of both sides of the panel 13-1. Edge sheaths 17-2 are provided at the edges on both sides of the panel 13-2. Panel 13 - 1 and panel 13 - 2 , in which edge sheaths 17 - 1 and 17 - 2 are fitted in advance, are connected via support body 11 .

The support body 11 may include a frame 111 having the electrical connection portion 15 and a guide beam 118 receiving the frame 111 . As in the configuration example of FIG. 11A , the frame 111 and the guide beam 118 may be formed separately or integrally. When the frame 111 receives the panel 13-1 and the panel 13-2 from both sides, the bridge electrode 112 of the connection part 15 and the outer side of the edge sheath 17-1 of the panel 13-1 and the edge sheath 17 of the panel 13-2 The outer side of -1 is in contact on both sides. Accordingly, electrical connection is established between the reflection surface 105-1 of the electromagnetic wave reflection device 10-1 and the reflection surface 105-2 of the electromagnetic wave reflection device 10-2.

By fitting the frame 111 connecting the panel 13 - 1 and the panel 13 - 2 into the guide beam 118 , the frame 111 and the guide beam 118 are integrated to form the support body 11 .

FIG. 11B shows the state of the electromagnetic wave reflection device 10 before connection. In each of the electromagnetic wave reflecting devices 10-1 to 10-3, a frame 111 having an electrical connection portion 15 is pre-installed on one side edge of the panel 13, and a guide beam 118 is installed on the other side edge. The reflection surfaces 105 of the electromagnetic wave reflection devices 10-1 to 10-3 may be any of the structures shown in FIGS. 6A to 6D.

The frame 111 is formed to be able to fit into a guide beam 118 provided in another electromagnetic wave reflection device 10 . The guide beam 118 is formed to be able to receive the frame 111 provided on another electromagnetic wave reflection device 10 . For example, the guide beam 118 of the electromagnetic wave reflecting device 10-1 receives the frame 111 of the electromagnetic wave reflecting device 10-2. The guide beam 118 of the electromagnetic wave reflecting device 10-2 receives the frame 111 of the electromagnetic wave reflecting device 10-3. By combining and integrating electromagnetic wave reflectors 10 of fixed dimensions, it is possible to cope with the length of the production line. The assembly work may be performed on-site in the factory. Each of the electromagnetic wave reflecting devices 10-1 to 10-3 has a simple structure and is easy to transport.

FIG. 11C shows the state of the connected electromagnetic wave reflecting device 10 . The frame 111 and the guide beam 118 are integrated to form the support body 11 . The electromagnetic wave reflecting fence 100 may be formed by connecting a plurality of electromagnetic wave reflecting devices 10 - 1 , 10 - 2 , and 10 - 3 via the support body 11 . The electrical connection portion 15 of the frame 111 suppresses the discontinuity of the reflected current at the connecting portion between the panels 13 .

By pre-installing the base 119 on at least one of the guide beam 118 and the frame 111 , the connected electromagnetic wave reflecting devices 10 - 1 to 10 - 3 stand independently on the installation surface through the base 119 of the support body 11 . It is also possible to make the cover 29 cover the edge of the panel 13 of the electromagnetic wave reflector 10 - 3 located at the endmost part, so as to protect the edge sheath 17 and the guide beam 118 .

Fig. 12 and Fig. 13 show a mechanism for strengthening the connection when connecting a plurality of electromagnetic wave reflecting devices 10-1, 10-2. (A) of Fig. 12 is a front view of the electromagnetic wave reflecting fence 100, (B) of Fig. 12 is a side view showing the state before the reinforcement mechanism 125 is fastened, and (C) of Fig. 12 is a side view showing the state after the reinforcement mechanism 125 is fastened. State side view. FIG. 13 is a configuration example of the reinforcing mechanism 125 . (A) of FIG. 13 shows the guide groove 129 formed on the mounting surface 127 a of the cover 127 used for the reinforcement mechanism 125 which is mounted to the panel 13 . (B) of FIG. 13 shows the state of cross section A and cross section B of FIG. 13 (A) .

In order to improve connection strength and electrical connectivity, the reinforcement mechanism 125 shown in FIGS. 12 and 13 may be appropriately used to the extent that the reflection characteristics are not deteriorated. A hole 126 is formed in the panel 13, a pin 128 is passed through the hole, and a cover 127 is attached to the surface of the panel 13 opposite to the reflective surface. By moving the pin 128 along the guide groove 129 formed in the attachment surface 127a of the cover 127, the panel 13 can be brought into pressure contact with the support body 11 from both sides. The position of the hole 126 formed in the panel 13 is slightly moved toward the support body 11 by tightening the reinforcement mechanism 125 . Utilizing the elastic force of the panel 13, the connection between the edge of the panel 13 and the connection portion 15 (see FIG. 13 ) of the support body 11 becomes reliable.

The mechanism for strengthening the connection of the plurality of electromagnetic wave reflecting devices 10 is not limited to the examples shown in FIGS. 12 and 13 , and an appropriate zipper mechanism, ratchet, etc. may be used within the range that does not hinder the electromagnetic wave reflection characteristics. Designs of the edge sheath 17 and the connection portion 15 may be appropriately adjusted assuming such a crimping process.

＜Application to production lines＞

FIG. 14 is a diagram illustrating the dimensions of the metareflector 102 . Set the transmitter to "Tx" and the receiver to "Rx". The transmitter Tx is for example a base station BS. The receiver Rx is, for example, a machine within the production line 3 . Let the distance from the transmitter Ts to the surface 102S of the metareflector 102 be d1, and let the distance from the surface 102S of the metareflector 102 to the receiver Rx be d2.

On the premise of use in a production line, the total distance D between d1 and d2 is 40m as an example (D=d1+d2=40m). The standard length of the production line is 80m. Assuming that base stations BS are arranged at both ends in the longitudinal direction of the production line, and two base stations BS provide a standard rectangular service area, D=40m.

The radius R of the first Fresnel zone when radio waves radiated from the transmitter Tx and reflected by the metareflector 102 reach the receiver Rx in the same phase is defined by the formula (1).

[mathematical formula 1]

Here, λ is the wavelength used.

FIG. 15 shows a specific example of the radius R of the first Fresnel zone derived from the formula (1). When the operating frequency is 28 GHz, d1 is 30 m, and d2 is 10 m, the radius R of the first Fresnel zone is 0.283 m. Under the same frequency, when d1 is 35m and d2 is 5m, the radius R is 0.216m.

When the operating frequency is 3.8 GHz, d1 is 30 m, and d2 is 10 m, the radius R of the first Fresnel zone is 0.770 m. Under the same frequency, when d1 is 35m and d2 is 5m, the radius R is 0.588.

It is preferable for the machine M arranged in the production line to receive the reflected wave from the electromagnetic wave reflecting device 10 in phase with the direct wave from the base station BS to improve the reception intensity. In the case of applying the electromagnetic wave reflection device 10 using the metareflector 102 to a production line, considering the first Fresnel band capable of in-phase reception, in the 28 GHz frequency band, as the minimum Size, preferably the length of one side is at least 0.5m or more. In the 3.8 GHz band, the minimum size of one metareflector 102 is preferably about 1 m in length on one side. As shown in FIG. 5B to FIG. 5D , when one panel 13 uses multiple metareflectors 102 , the size of each metareflector 102 preferably covers at least the first Fresnel zone.

Since the radius R of the first Fresnel zone does not depend on the relationship between the incident angle and the reflection angle, the same calculation is also applicable to the standard reflector 101 . In order to guide the radio waves incident on the standard reflector 101 to the receiver Rx with the same phase through normal reflection, the size of the standard reflector 101 is preferably 50 cm or more on one side.

When the metareflector 102 is used in a production line covered by a service area with a large aspect ratio, oblique incidence at any one of the angle of incidence and the angle of reflection becomes deep. Hereinafter, the arrangement relationship among the production line 3, the base station BS, and the electromagnetic wave reflection device 10 will be studied.

＜Configuration relationship of wireless transmission system＞

The configuration relationship of the wireless transmission system 1 will be described with reference to FIGS. 16A , 16B, 17A, and 17B. As described with reference to FIGS. 1 and 2 , the wireless transmission system 1 includes: a base station BS that transmits and receives radio waves in a frequency band of 1 GHz to 170 GHz; a production line 3 that is equipped with production machines that transmit and receive the radio waves; and an electromagnetic wave reflection device 10 along the At least a part of the configuration of the above-mentioned production line. The electromagnetic wave reflecting device 10 has a reflecting surface 105 that reflects radio waves in the above-mentioned frequency bands.

As will be described in detail below, the base station BS is preferably located on the side of the production line 3 rather than the extension line L horizontal to the reflection surface 105 . For example, the base stations BS may be arranged at both ends of the production line 3 in the longitudinal direction. The production machines in the production line 3 can communicate with the base station BS directly or via the electromagnetic wave reflecting device 10 in the above-mentioned frequency band.

FIG. 16A shows the mode 1 of reflection in the wireless transmission system 1 . In mode 1, as shown by the arrow of the solid line, the base station BS and the production line 3 are arranged in the following positional relationship: the electric wave emitted from the base station BS is incident at a deep angle relative to the vertical line of the reflecting surface 105 of the electromagnetic wave reflecting device 10, and is incident at a shallow angle. angle reflection. That is, in mode 1, radio waves are incident at an incident angle of 45 degrees or more, and are reflected such that the reflection angle is smaller than that of normal reflection.

In order to make the radio waves from the base station BS incident on the reflective surface 105 at a deep angle, the base station BS is preferably located on the side of the production line 3 from the extension line L of the electromagnetic wave reflection device 10, and at the end of the production line 3 in the longitudinal direction. By making the radio waves incident on the reflective surface 105 at a deep angle, the radio waves can be transmitted to the center of the production line 3 or its vicinity.

Figure 16B shows Mode 2 of reflection. In Pattern 2, the base station BS and the production line 3 are arranged in such a positional relationship that radio waves radiated from the base station BS are incident at a shallow angle to the perpendicular to the reflecting surface 105 and reflected at a deeper angle than the incident angle. That is, in mode 2, radio waves are incident at an angle of incidence of 45 degrees or less, and are reflected so that the reflection angle is larger than that of normal reflection.

In the case of mode 2, the base station BS is located on the side of the production line 3 compared to the extension line L horizontal to the reflection surface 105 of the electromagnetic wave reflection device 10, but is located on the side closer to the end of the production line 3 in the longitudinal direction. Location. As will be described below, in the case of the mode 2, the influence on the deviation of the oblique incident angle becomes larger.

Figure 17A shows the baseline robustness for Mode 1, and Figure 17B shows the baseline robustness for Mode 2. The reference robustness refers to the stability of the reflection angle when the incident angle is changed by 1 degree. The benchmark is robust when there is little change in the reflection angle with respect to a change of 1 degree in the angle of incidence.

In Fig. 17A, in mode 1, the abnormal angle θabn is changed to 7 kinds of 20°, 25°, 30°, 35°, 40°, 45° and 50°, and the variation of the reflection angle with respect to the incidence angle is estimated. change. The fluctuations of the reflection angles under the seven kinds of abnormal angles θabn are approximately the same and overlap each other, so they appear as a thick line in the figure.

As described with reference to FIG. 3B , the abnormal angle θabn is the difference between the reflection angle of normal reflection and the reflection angle of asymmetric reflection in asymmetric reflection in which radio waves are reflected at a reflection angle different from the incident angle. Changing the abnormal angle θabn from 20° to 50° is equivalent to controlling the reflection direction of the asymmetric reflection within an angle range of 30°.

In the range of the incident angle of 50° to 75° (deep incident), the reflection angle fluctuates as little as less than 1 degree with respect to a change of the incident angle of 1 degree, and is substantially constant regardless of the incident angle. It can be seen that the controllability of the reflection in the asymmetric reflection is high when the incident angle is deep. It is easy to guess that the trend shown in FIG. 17A showing little variation in the reflection angle is maintained even when the incident angle exceeds 75° and reaches around 90°.

In FIG. 17B , in pattern 2, the abnormal angle θabn was changed to seven types of 20°, 25°, 30°, 35°, 40°, 45°, and 50°, and the variation of the reflection angle with respect to the incident angle was estimated. In the range of incident angle 15° to 40° (shallow reflection), the variation of reflection angle with respect to a change of incident angle 1 degree varies according to incident angle, and the deviation becomes larger with abnormal angle θabn.

When the anomalous angle θabn is small, that is, the difference in reflection angle from normal reflection is small, the incident angle dependence of the variation in the reflection angle is small. If the abnormal angle θabn is increased, that is, the change of the reflection direction based on the metareflector 102 is increased, the variation of the reflection angle with respect to the change of 1 degree of the incident angle becomes very large, and the variation of the reflection angle also depends on the incident angle. And vastly different. In the shallow range where the incident angle is 15° to 40°, controllability of reflection in asymmetric reflection is not good.

According to FIG. 17A and FIG. 17B , when the base station BS is arranged in the production line 3, from the viewpoint of suppressing fluctuations in the reflection angle depending on the incident angle, it is preferable that the incident angle on the reflecting surface 105 of the electromagnetic wave reflecting device 10 be 50° or more. The angular position of the configuration base station BS. Therefore, the configuration relationship of FIG. 16A is more preferable than the configuration shown in FIG. 16B.

FIG. 18 is a diagram illustrating a quantification method of benchmark robustness. The baseline robustness of FIGS. 17A and 17B is evaluated in the following order. A certain incident angle θi and reflection angle θr are used as input, and the phase jump Φ(x) is obtained by using the function f of the phase jump distribution. Here, x is a position in the x direction on the reflective surface. The phase jump refers to a phase amount applied to a reflected wave in order to reflect the reflected wave at a desired angle. The phase jump distribution dΦ/dx is expressed as: sinθr-sinθi=(λ/2π)(dΦ/dx). Here, λ is the wavelength used. If non-patent literature is used, 94.075142 (2016) of B issue of "PHYSICAL REVIEW" is the surface impedance ZS and fluctuation impedance η recorded in "PERFECT CONTROL OF REFLECTIONAND REFRACTION USING SPATIALLY DISPERSIVE METASURFACES" published by the author V.S.Asadchy et al. Then, the function f for obtaining the phase jump distribution Φ(x) is represented by Mathematical Expression 2.

[mathematical formula 2]

arg() is a function representing an angle (argument) on a complex number. The surface impedance Zs(x) is represented by Mathematical Expression 3.

[mathematical formula 3]

Next, change the incident angle by 1 degree, take the changed incident angle and reflection angle' as input, and calculate the phase jump Φ'(x) according to the phase jump distribution function f.

Find the minimum reflection angle' of Φ'(x)-Φ(x), and regard it as the variation of the reflection angle relative to the incident angle. 17A and 17B are graphs plotting the obtained variation of the reflection angle as a function of the incident angle.

FIG. 19A shows the variation of the phase jump of mode 1. FIG. The horizontal axis is the position (m), and the vertical axis is the phase (degree). In the Deep-in Shallow-out in FIG. 19A , the reflection angle θr is fixed at 30 degrees, and the incident angle θi is oscillating at 68.5°, 70°, and 71.5°. In the incidence at a deep angle, even if the incidence angle is changed within a range of 3°, the distribution of the phase jump does not change much.

FIG. 19B shows the variation of the phase jump of Mode 2. FIG. The horizontal axis is the position (m), and the vertical axis is the phase (degree). In the Shallow-in Deep-out shown in FIG. 19B , the reflection angle θr is fixed at 60 degrees, and the incident angle θi is oscillated to be 18.5°, 20°, and 21.5°. In the shallow angle of incidence, if the incidence angle is changed within a range of 3° as in FIG. 19A , the distribution of the phase jump is greatly shifted by the incidence angle.

As can be seen from FIGS. 19A and 19B , the arrangement of FIG. 16A is more preferable than that of FIG. 16B in terms of making the distribution of the phase jump of the radio waves incident on the electromagnetic wave reflecting device 10 uniform. In the arrangement of FIG. 16B , the base station BS is arranged at a position where radio waves from the base station BS enter the reflecting surface 105 of the electromagnetic wave reflecting device 10 at an incident angle of 50 degrees or more.

As mentioned above, although this invention was demonstrated based on the specific structural example, various deformation|transformation and substitution are possible in the range which does not deviate from invention. As long as the metareflector 102 can control the reflection characteristics such as the reflection phase, any structure can be adopted, as long as the periodic structure with frequency selectivity or wavelength selectivity is appropriately designed.

The electromagnetic wave reflecting device 10 can be arranged on one side along the long side of the production line 3 as shown in FIG. 16A , or can be arranged on both sides of the production line 3 as shown in FIG. 2 . When the production line 3 is bent into an L shape, the electromagnetic wave reflecting device 10 may be installed in each area forming a rectangular area, or the electromagnetic wave reflecting device 10 may be installed in any one of the main lines. In either case, the base station BS is arranged at a position where radio waves enter the reflecting surface 105 of the electromagnetic wave reflecting device 10 at a deep incident angle.

The machines in the production line 3 do not need to receive only the reflected waves from the electromagnetic wave reflecting device 10, but may directly receive the radio waves radiated from the base station BS. In this case, reception diversity can also be performed by in-phase reception. When the base stations BS are arranged on both sides in the longitudinal direction of the production line 3, coordinated base stations may be used.

As shown in FIG. 11A , each electromagnetic wave reflecting device 10 may be transported with the frame 111 attached to one of the opposing edges of the panel 13 and the guide beam 118 attached to the other. In this case, the on-site installation work of components is omitted, and assembly becomes easy. Alternatively, the panel 13 may be transported with only the frame 111 attached thereto, and may be assembled on site using the guide beam 118 . In addition, as shown in FIG. 5A , the positioning of the metasurface on the panel 13 may be performed at the installation site of the electromagnetic wave reflecting device 10 .

The electromagnetic wave reflecting device and the wireless transmission system of the embodiment contribute to the realization of a smart factory.

This application claims priority based on Japanese Patent Application No. 2020-064578 filed on March 31, 2020, including the entire content of the patent application.

Explanation of reference signs

1...wireless transmission system; 3...production line; 10, 10A～10E, 10-1, 10-2...electromagnetic wave reflection device; 11...support body; 13, 13-1, 13-2...panel; 15, 15A～ 15E...connecting part; 16...rod; 17, 17-1, 17-2...edge sheath; 19...slanted column; 100...electromagnetic wave reflection fence; 101...standard reflector; 102...superstructure reflector; 105...reflection Surface; 111, 111A～111E…frame; 112, 112A, 114…bridge electrode; 118…guiding beam; 125…strengthening mechanism; 131…conductor; 132, 133…dielectric; BS, BS1, BS2…base station; , WT2...Wireless Communication Department; SY...symmetric reflection area; AS...asymmetric reflection area.

Claims (10)

1. A wireless transmission system, wherein: a base station that transmits and receives radio waves in a desired frequency band selected from frequency bands ranging from 1 GHz to 170 GHz; and The electromagnetic wave reflecting device is arranged along at least a part of a production line of a production machine that transmits and receives the radio wave, and has a reflective surface that reflects the radio wave. 2. The wireless transmission system according to claim 1, wherein, The base station is located on a side closer to the production line than the extended surface of the reflective surface. 3. The wireless transmission system according to claim 1 or 2, wherein, The electromagnetic wave reflecting device is arranged on both sides of the production line along the at least a part of the production line. 4. The wireless transmission system according to any one of claims 1 to 3, wherein: The base station includes a first base station and a second base station arranged at both ends of the production line in the length direction, The production machine is capable of communicating with at least one of the first base station and the second base station in the frequency band. 5. The wireless transmission system according to any one of claims 1 to 4, wherein: The reflective surface has a symmetrical reflection area that reflects the radio wave at the same reflection angle as the incident angle of the radio wave, and an asymmetric reflection area that reflects the radio wave at a different reflection angle from the incident angle. 6. The wireless transmission system according to claim 5, wherein, The incident angle of the radio wave transmitted from the base station to the asymmetric reflection area is 50° or more. 7. The wireless transmission system according to claim 5 or 6, wherein, The area of the asymmetric reflection region covers at least the first Fresnel zone determined by the frequency of the radio wave. 8. The wireless transmission system according to claim 1, wherein, The base station is disposed at a position where the incident angle of the radio waves transmitted from the base station to the reflecting surface is 50° or greater. 9. The wireless transmission system according to any one of claims 1 to 8, wherein: The reflective surface has meshes, grids, or hole arrays formed to reflect the density of radio waves in the frequency band, and the average period of the meshes, grids, or hole arrays formed in the density is the frequency band less than 1/5 of the free-space wavelength. 10. The wireless transmission system according to any one of claims 1 to 9, wherein: A plurality of the electromagnetic wave reflecting devices are mechanically and electrically connected.

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